Oracle7 Server Distributed Systems Volume II: Replicated Data

Snapshot and Snapshot Refresh Group Views

Oracle provides the following views that have information about snapshots and snapshot refresh groups.

DBA_SNAPSHOTS

USER_REFRESH

USER_REFRESH_CHILDREN

DBA_SNAPSHOTS View

The DBA_SNAPSHOTS catalog view lists information about all of the snapshots in a database.

Column Description
OWNER Owner of the snapshot.
NAME Name of the view used by users and applications for querying and updating the snapshot.
TABLE_NAME Table in which the snapshot is stored (it has an extra column for the master rowid).
MASTER_VIEW View of the master table, owned by the snapshot owner, used for refreshes.
MASTER_OWNER Owner of the master table.
MASTER Master table that this snapshot copies.
MASTER_LINK Database link name to the master site.
CAN_USE_LOG YES if this snapshot can use a snapshot log, NO if this snapshot is too complex to use a log.
UPDATABLE `YES' indicates snapshot is updatable; `NO' indicates read-only.
LAST_REFRESH Date and time at the master site of the last refresh.
ERROR Error returned last time an automatic refresh was attempted or number of failed attempts since last successful attempt.
TYPE Type of refresh for all automatic refreshes: COMPLETE, FAST, FORCE.
NEXT Date function used to compute next refresh dates.
START_WITH Date function used to compute next refresh dates.
REFRESH_GROUP Group identifier for consistent refresh.
UPDATE_TRIG Name of the trigger that fills in the UPDATE_LOG for an updatable snapshot.
UPDATE_LOG Name of the table that logs changes to an updatable snapshot.
QUERY Query used to create the snapshot.

Table 13 - 29. DBA_SNAPSHOTS View

USER_REFRESH View

The USER_REFRESH view lists each refresh group found in the database, and includes information about the refresh interval for each group.

Column Description
ROWNER Owner of the refresh group.
RNAME Name of the refresh group.
REFGROUP ID number of the refresh group.
IMPLICIT_DESTROY Implicit delete flag. If this value is Y, Oracle deletes the refresh group after you have subtracted the last member from the group.
JOB ID number of the job used to execute the automatic refresh of the snapshot group. You can use this information to query the USER_JOBS view for more information about the job.
NEXT_DATE Date when the members of the group will next be refreshed.
INTERVAL The function used to calculate the interval between refreshes.
BROKEN Flag used to indicate a problem with the refresh group. If the value of the broken flag is Y, Oracle will not refresh the group, even if it is scheduled to be refreshed.

Table 13 - 30. USER_REFRESH View

USER_REFRESH_ CHILDREN View

The USER_REFRESH_CHILDREN view lists the members of each refresh group owned by the user, and includes information about the refresh interval for each member.

Column Description
OWNER Owner of the refresh group member.
NAME Name of the refresh group member.
TYPE Type of the refresh group member; for example, SNAPSHOT.
ROWNER Owner of the refresh group.
RNAME Name of the refresh group.
REFGROUP ID number of the refresh group.
IMPLICIT_DESTROY Implicit delete flag. If this value is Y, Oracle deletes the refresh group after you have subtracted the last member from the group.
JOB ID number of the job used to execute the automatic refresh of the snapshot refresh group. You can use this information to query the USER_JOBS view for more information about the job.
NEXT_DATE Date when the members of the group will next be refreshed.
INTERVAL The function used to calculate the interval between refreshes.
BROKEN Flag used to indicate a problem with the refresh group. If the value of the broken flag is Y, Oracle will not refresh the group, even if it is scheduled to be refreshed.

Table 13 - 31. USER_REFRESH_CHILDREN View

Column	Description
OWNER	Owner of the snapshot.
NAME	Name of the view used by users and applications for querying and updating the snapshot.
TABLE_NAME	Table in which the snapshot is stored (it has an extra column for the master rowid).
MASTER_VIEW	View of the master table, owned by the snapshot owner, used for refreshes.
MASTER_OWNER	Owner of the master table.
MASTER	Master table that this snapshot copies.
MASTER_LINK	Database link name to the master site.
CAN_USE_LOG	YES if this snapshot can use a snapshot log, NO if this snapshot is too complex to use a log.
UPDATABLE	`YES' indicates snapshot is updatable; `NO' indicates read-only.
LAST_REFRESH	Date and time at the master site of the last refresh.
ERROR	Error returned last time an automatic refresh was attempted or number of failed attempts since last successful attempt.
TYPE	Type of refresh for all automatic refreshes: COMPLETE, FAST, FORCE.
NEXT	Date function used to compute next refresh dates.
START_WITH	Date function used to compute next refresh dates.
REFRESH_GROUP	Group identifier for consistent refresh.
UPDATE_TRIG	Name of the trigger that fills in the UPDATE_LOG for an updatable snapshot.
UPDATE_LOG	Name of the table that logs changes to an updatable snapshot.
QUERY	Query used to create the snapshot.

Column	Description
ROWNER	Owner of the refresh group.
RNAME	Name of the refresh group.
REFGROUP	ID number of the refresh group.
IMPLICIT_DESTROY	Implicit delete flag. If this value is Y, Oracle deletes the refresh group after you have subtracted the last member from the group.
JOB	ID number of the job used to execute the automatic refresh of the snapshot group. You can use this information to query the USER_JOBS view for more information about the job.
NEXT_DATE	Date when the members of the group will next be refreshed.
INTERVAL	The function used to calculate the interval between refreshes.
BROKEN	Flag used to indicate a problem with the refresh group. If the value of the broken flag is Y, Oracle will not refresh the group, even if it is scheduled to be refreshed.